The theory of convergence predicts that, given
similar selective regimes, both present and past, unrelated
ecological communities will show similar attributes. Mild
Pleistocene climate, highly infertile soils, and similar fire
regimes explain the remarkable convergence between mediterranean-
type vegetation from South Africa (fynbos) and
Australia (kwongan). Heathlands in the Aljibe Mountains, at
the western end of the Mediterranean basin, constitute a single
vegetation type within the Mediterranean region.
We studied the association between endemism and plant
life form in a flora from environmentally similar areas of the
South African Cape region (fynbos) and the Aljibe Mountains
by contingency table analysis. We included two non-acid,
neighbouring areas to the latter region in the analysis as
contrasts. We also compared the patterns of variation in three
components of biodiversity (species richness, endemism level
and taxonomic singularity) of fynbos and Aljibe heathland
woody plant communities along similar soil fertility gradients
by means of two-way ANOVAs.
At the regional (flora) level, our results show two common
features in the biological aspects of endemism between the
two regions: (1) edaphic endemism and (2) association of
endemism with the shrub growth form. At the community
level, we detected strong similarities in the patterns of variation
of endemism and taxonomic singularity of woody communities
from both regions along an ecological gradient related
to soil fertility. We interpret these similarities, both at the
regional and community levels, as suggestive of convergence
between fynbos and Aljibe heathland.